With pattern assignment, the error messages are now different in 2.19
libraries since a parenthesized expression looks like you might be
trying to do a pattern assignment.
Change-Id: I00105ea4cb5dbe8c8b328fb2e665200f3dc33722
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/286870
Auto-Submit: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Jake Macdonald <jakemac@google.com>
Commit-Queue: Jake Macdonald <jakemac@google.com>
